JPWO2018131711A1 - Method for producing saccharide-containing cellulose hydrolyzate - Google Patents

Abstract

The present invention includes a step (1) of dissolving cellulose in an acid aqueous solution, a step (2) of mixing a cellulose hydrolyzed solid catalyst in an acid aqueous solution in which cellulose is dissolved, and a step of adsorbing at least a part of cellulose on the solid catalyst ( 3) and a step (4) of heating a solid catalyst adsorbing cellulose in the presence of water to hydrolyze cellulose to obtain a hydrolyzate containing saccharides. It relates to a manufacturing method. The present invention provides a new method for synthesizing glucose by hydrolyzing cellulose using a solid catalyst.

Description

The present invention relates to a method for producing a saccharide-containing cellulose hydrolyzate. More specifically, the present invention relates to a method for producing a glucose-containing cellulose hydrolyzate or a sorbitol-containing cellulose hydrolysate.
This application claims the priority of Japanese Patent Application No. 2017-004847 filed on Jan. 16, 2017, the entire description of which is specifically incorporated herein by reference.

  A method for producing a sugar-containing liquid by hydrolyzing cellulose or hemicellulose using a solid catalyst is known (Patent Documents 1 and 2). For decomposing cellulose and biomass, a ball mill method (Non-patent Document 1) is used for amorphization of cellulose as a pretreatment. However, this pretreatment requires a large amount of energy, which has been an obstacle to practical use. In addition, a method using inexpensive phosphoric acid for dissolving cellulose to make it amorphous is known (Non-patent Document 2). However, the cellulose solution has a high viscosity, so the operability is poor, and in order to take out the cellulose from phosphoric acid, a large amount of water must be added to precipitate the cellulose. There is a problem of requiring a lot of energy.

  Recently, we reported a method of decomposing cellulose with a solid catalyst using the ball mill method (Non-patent Document 3).

Patent Document 1: WO2011 / 036955
Patent Document 2: WO2014 / 007295

Non-patent document 1: Energy Fuels., 2006, 20, 807
Non-Patent Document 2: Biomacromolecules, 2006, 7, 644
Non-Patent Document 3: ACS Catal., 2013, 3, 581
The entire descriptions of Patent Literatures 1 and 2 and Non-Patent Literatures 1, 2, and 3 are each specifically incorporated herein by reference.

  In the method described in Non-Patent Document 3, a solid catalyst made of a carbon material having a weak acid point has the ability to hydrolyze cellulose. However, in order to synthesize glucose at a high yield, the carbon material and cellulose are combined together. Ball milling is required and the above problems are not overcome.

  The purpose of this pretreatment is to make the cellulose amorphous and to form a contact between the carbon material and cellulose. Development of a low-energy pretreatment method that can achieve the same effect and hydrolysis of cellulose using this pretreatment method Thus, a method for synthesizing glucose in a high yield is desired.

  An object of the present invention is to provide a new method for synthesizing glucose by hydrolyzing cellulose using a solid catalyst.

  When the cellulose is dissolved with phosphoric acid and then a solid catalyst made of a carbon material is further added to the solution, the present inventors have added solubilized cellulose containing partially hydrolyzed cellulose and non-hydrolyzed cellulose due to the interaction between cellulose and carbon. It has been found that the adsorption of crystalline cellulose occurs, and then the hydrolysis of cellulose can be promoted by heating in the presence of a small amount of water.

In particular, when cellulose is partially hydrolyzed in phosphoric acid, it becomes more easily adsorbed to the carbon material, and the viscosity of the solution is drastically reduced. It has been found that the amount of water used in the process of adsorption of amorphous cellulose and separation of the carbon material after adsorption from the solution can be further suppressed.
The present invention has been completed based on these findings.

The present invention is as follows.
[1]
A step (1) of dissolving cellulose in an acid aqueous solution;
A step (2) of mixing a cellulose-hydrolyzed solid catalyst with an acid aqueous solution in which cellulose is dissolved;
Step (3) of adsorbing at least a part of cellulose on the solid catalyst, and heating the solid catalyst adsorbing cellulose in the presence of water to hydrolyze the cellulose to obtain a hydrolyzate containing saccharides Step (4),
A method for producing a saccharide-containing cellulose hydrolyzate comprising
[2]
The production according to [1], wherein the product after at least partially hydrolyzing and dissolving at least a part of cellulose in an aqueous acid solution is subjected to step (2) during and / or after step (1). Method.
[3]
Partial hydrolysis is a manufacturing method as described in [2] performed at the temperature of 40-80 degreeC.
[4]
The production method according to any one of [1] to [3], wherein at least a part of the cellulose used in the step (1) has an I-type crystal structure.
[5]
The production method according to any one of [1] to [4], wherein the acid in the acid aqueous solution used in step (1) is at least one acid selected from the group consisting of phosphoric acid, sulfuric acid, and hydrochloric acid.
[6]
The production method according to [5], wherein the acid aqueous solution used in step (1) is an orthophosphoric acid aqueous solution.
[7]
The production method according to [6], wherein the phosphoric acid concentration of the aqueous orthophosphoric acid solution used in step (1) is 75% or more.
[8]
The production method according to any one of [1] to [7], wherein the adsorption of cellulose on the solid catalyst in the step (3) is performed by adding water to the acid aqueous solution.
[9]
The production according to any one of [1] to [8], wherein the solid catalyst adsorbed with cellulose obtained in the step (3) is separated from the acid aqueous solution and removed from the acid, and then subjected to the step (4). Method.
[10]
The cellulose adsorbed on the solid catalyst in the step (3) includes at least one selected from the group consisting of partially hydrolyzed cellulose, amorphous cellulose, and cellulose II, according to any one of [1] to [9]. Manufacturing method.
[11]
The production method according to any one of [1] to [10], wherein the cellulose hydrolyzed solid catalyst is at least one catalyst selected from the group consisting of a carbon catalyst, boron nitride, and a transition metal supported catalyst.
[12]
The production method according to [11], wherein the carbon catalyst is a porous carbon material, and the porous carbon material can be activated carbon or carbon black.
[13]
The transition metal-supported catalyst is a catalyst in which a transition metal is supported on a solid support, and the solid support is at least one material selected from the group consisting of a carbon-based material and boron nitride. .
[14]
The production method according to any one of [1] to [13], wherein the mass ratio of cellulose to catalyst in the solid catalyst on which cellulose is adsorbed is in the range of 100: 1 to 10,000.
[15]
The manufacturing method in any one of [1]-[14] whose cellulose used at a process (1) is vegetable biomass.

  According to the present invention, amorphous cellulose or the like is strongly resistant to a solid catalyst made of a carbon material or the like by a pretreatment that does not use a ball mill method and in addition has reduced energy compared to the conventional phosphoric acid method (Non-Patent Document 2). A contact state can be formed, and glucose is obtained in high yield when hydrolysis conditions by heating are applied to this sample.

FIG. 1 shows the results of hydrolysis of cellulose pretreated with phosphoric acid. FIG. 2 shows the results of size exclusion chromatography of the solution after 0, 3, 7, and 9 days after the start of stirring for partial hydrolysis of cellulose. FIG. 3 shows the influence of the presence or absence of liquefied cellulose adsorption in the hydrolysis reaction. FIG. 4 shows the results of the hydrolysis reaction of cellulose when partial hydrolysis of the cellulose solution was performed at 60 ° C. FIG. 5 shows the results of the hydrolysis reaction of cellulose when the type of activated carbon is changed. FIG. 6 shows the results of the hydrolysis reaction of cellulose when the amount ratio of activated carbon and cellulose is changed. FIG. 7 shows the results of the hydrolysis reaction of cellulose when the solvent used for the precipitation (adsorption) of partially hydrolyzed cellulose was changed.

The present invention relates to a method for producing a saccharide-containing cellulose hydrolyzate comprising the following steps (1) to (4).
Step (1): dissolving cellulose in an acid aqueous solution,
Step (2): A cellulose hydrolyzed solid catalyst is mixed with an acid aqueous solution in which cellulose is dissolved.
Step (3): adsorbing at least a part of cellulose on the solid catalyst,
Step (4): The solid catalyst on which cellulose is adsorbed is heated in the presence of water to hydrolyze the cellulose to obtain a hydrolyzate containing saccharides.

Process (1)
Step (1) is a step of dissolving cellulose in an acid aqueous solution.
The cellulose used in the step (1) can be, for example, plant biomass, and the cellulose that is the main component of the plant biomass exhibits crystallinity by binding two or more cellulose molecules through hydrogen bonding. It has an I-type crystal structure. In the step (1), cellulose having such crystallinity can be used as it is as a raw material. However, the cellulose may be one that has been subjected to crystallinity reduction and / or partial hydrolysis treatment before dissolution in an acid aqueous solution. However, even if crystalline cellulose is used as it is, depending on the type and concentration of the acid aqueous solution, it can be dissolved relatively easily. Therefore, using crystalline cellulose as it is requires extra steps and energy. It is unnecessary and preferable.

  Cellulose with reduced crystallinity may be partially reduced in crystallinity or completely or almost completely lost. The type of the crystallinity reduction treatment is not particularly limited, but may be a crystallinity reduction treatment that can break the hydrogen bond and at least partially generate a single-chain cellulose molecule. By using cellulose containing at least partially a single-chain cellulose molecule as a raw material, dissolution in an acid aqueous solution can be accelerated.

  Examples of a method for physically breaking hydrogen bonds between cellulose molecules include a pulverization treatment. The pulverizing means is not particularly limited as long as it has a function capable of being pulverized. For example, the system of the apparatus may be either dry type or wet type, and the pulverization system of the apparatus may be either batch type or continuous type. Furthermore, the crushing force of the apparatus can be any of impact, compression, shear, friction and the like.

  The acid of the acid aqueous solution used in the step (1) is not particularly limited as long as it is an acid capable of dissolving cellulose in the aqueous solution, and can be an inorganic acid, and preferably includes, for example, phosphoric acid, sulfuric acid, and hydrochloric acid. And at least one acid selected from the group. The phosphoric acid aqueous solution can be, for example, an orthophosphoric acid aqueous solution. The acid concentration of the acid aqueous solution used in step (1) is not particularly limited as long as it is a concentration capable of dissolving cellulose, and the concentration capable of dissolving cellulose varies depending on the type of acid. For example, in the case of an orthophosphoric acid aqueous solution, cellulose can be dissolved if the phosphoric acid concentration is 75% or more. From the viewpoint of easier dissolution of cellulose, it is 80% or more, more preferably 85% or more. In the case of sulfuric acid, 60% or more, and in the case of hydrochloric acid, 30% or more, cellulose can be dissolved.

  The cellulose dissolved in the acid aqueous solution is hydrolyzed by the action of acid and water. In the step (1), during the dissolution of the cellulose (in parallel with the dissolution of the cellulose) and / or after the dissolution of the cellulose, at least a part of the cellulose is at least partially hydrolyzed in the acid aqueous solution to reduce the molecular weight and thereby the aqueous solution. It is preferable to reduce the viscosity of Even if the cellulose dissolved in the acid aqueous solution is not hydrolyzed, it is adsorbed to the solid catalyst in steps (2) and (3), but undergoes hydrolysis to become partially hydrolyzed cellulose. Thus, the adsorption onto the solid catalyst is facilitated, and the yield of sugar by heating hydrolysis in the subsequent step (4) can be improved. It should be noted that sugar (glucose) may be produced by hydrolysis of cellulose by acid in an acid aqueous solution, although it depends on conditions, although it is a small amount.

  After dissolving the cellulose in the acid aqueous solution, it is preferable to further promote at least partial hydrolysis of the cellulose by, for example, holding an acid aqueous solution in which the cellulose is dissolved for 1 minute to 10 days. The time for hydrolysis of cellulose at this stage can be appropriately determined in consideration of the type and concentration of acid, the concentration of cellulose, the treatment temperature, the desired degree of hydrolysis of cellulose, and the like. The days are merely examples and are not intended to be limited to this range. Processing temperature can be the range of normal temperature (0-40 degreeC), for example, can also melt | dissolve and hydrolyze by heating. Although there is no restriction | limiting in particular in heating temperature, For example, it is the range of 30 to 100 degreeC, Preferably it is the range of 40 to 80 degreeC. At normal temperature, it is preferable to hold for 1 day or more, more preferably 3 days or more. On the other hand, if the holding time is too long, dissolved cellulose precipitates and solid by-products may be formed, and the yield of glucose may be reduced. At room temperature, it is preferable to keep it for 9 days or less. In the case of 40 to 80 ° C., depending on the temperature, it can be in the range of 1 minute to 240 minutes, and in the case of 60 ° C., it can be in the range of 10 to 120 minutes. In any case, it can be determined appropriately in consideration of the yield of glucose by final hydrolysis.

  The concentration of cellulose in the acid aqueous solution in which cellulose is dissolved is determined in consideration of the amount and state of cellulose adsorbed on the solid catalyst in step (3), the progress of heating hydrolysis of cellulose in the subsequent step (4), etc. It can be determined as appropriate. The cellulose concentration can be, for example, in the range of 5 to 500 g / L, preferably in the range of 10 to 200 g / L, and more preferably in the range of 15 to 100 g / L. However, these numerical ranges are examples and are not limited.

Step (2)
A cellulose hydrolysis solid catalyst is mixed with the acid aqueous solution in which cellulose is dissolved in step (1). The cellulose hydrolysis solid catalyst will be described later. In the present invention, the solid catalyst is mixed with an aqueous acid solution in which cellulose is dissolved. Specifically, a solid catalyst is added to an acid aqueous solution in which cellulose is dissolved, and further mixed by stirring. Stirring is preferably performed so that the solid catalyst is substantially uniformly dispersed in the acid aqueous solution. The amount of the solid catalyst added to the aqueous acid solution is the kind of the solid catalyst, the concentration of cellulose in the aqueous acid solution, the amount and state of cellulose adsorbed on the solid catalyst in step (3), and the heating and hydrolysis of cellulose in the subsequent step (4). It can be appropriately determined in consideration of the progress of decomposition. The amount of the solid catalyst added to the aqueous acid solution can be, for example, in the range of 2 to 500 g / L, preferably in the range of 5 to 200 g / L, and more preferably in the range of 10 to 100 g / L. However, these numerical ranges are examples and are not limited.

Process (3)
At least a part of cellulose is adsorbed on the solid catalyst mixed with the acid aqueous solution in the step (2). When the acid is phosphoric acid, the adsorption of cellulose on the solid catalyst is partially adsorbed when the solid catalyst is added in Step 2, but can be further promoted by adding water to the acid aqueous solution. In the phosphoric acid aqueous solution, when the phosphoric acid concentration decreases, the solubility of cellulose decreases, and as a result, the cellulose (including partially hydrolyzed cellulose) in the aqueous solution is adsorbed on the solid catalyst. A solid catalyst adsorbing cellulose (including partially hydrolyzed cellulose) can be obtained by separating the solid catalyst adsorbing cellulose (including partially hydrolyzed cellulose) from the acid aqueous solution and removing the acid if necessary. . In the case of sulfuric acid and hydrochloric acid, it can be the same as phosphoric acid.

  The cellulose adsorbed on the solid catalyst in the step (3) can contain at least one selected from the group consisting of partially hydrolyzed cellulose, amorphous cellulose and cellulose II. The mass ratio of cellulose to catalyst in the solid catalyst on which cellulose is adsorbed is not particularly limited, but can be, for example, in the range of 100: 1 to 10,000. In consideration of the conditions of heat hydrolysis in the step (4), for example, the range may be 100: 10 to 1000.

  The solid catalyst having adsorbed cellulose can be washed with water, for example, in order to remove the acid. Although the acid is removed by washing with water, a part of the acid may remain, and the remaining acid is considered to promote the hydrolysis of cellulose together with the solid catalyst during the heating hydrolysis in the step (4). However, the remaining acid may be mixed in the hydrolyzate containing the sugar obtained in the step (4), and excessive remaining of the acid is not preferable. The remaining of the acid with respect to the solid catalyst in the step (3) can be appropriately adjusted in consideration of this point.

<Cellulose hydrolysis solid catalyst>
The cellulose hydrolysis solid catalyst is not particularly limited as long as it can catalyze the hydrolysis of plant biomass. However, the cellulose hydrolysis solid catalyst has a β-1,4 glycosidic bond between glucose forming cellulose as a main component. It preferably has an activity to hydrolyze a glycosidic bond, as typified. Furthermore, it is appropriate that the cellulose hydrolysis catalyst used in the present invention has an adsorption ability for dissolved cellulose containing amorphous cellulose in the step (3). The catalyst that has adsorbed the regenerated cellulose containing amorphous cellulose in step (3) contains saccharides by efficiently hydrolyzing the adsorbed cellulose by heating in the presence of water in step (4). A hydrolyzate can be obtained. Details will be described later.

  Examples of the catalyst having the activity of hydrolyzing glycosidic bonds and the ability to adsorb dissolved cellulose containing amorphous cellulose include carbon materials, boron nitride (hexagonal h-BN), and transition metal supported catalysts. The carbon material and boron nitride have both catalytic activity and adsorption capacity, whereas in the transition metal supported catalyst, the transition metal mainly contributes to the catalytic activity and the catalyst carrier contributes to the adsorption capacity. These catalysts can be used alone or in combination of two or more.

  Examples of the “carbon material” include activated carbon, carbon black, graphite and the like. These carbon materials may be used alone or in combination of two or more. The shape of the carbon material is preferably porous and / or fine particles in terms of improving reactivity by expanding the contact area with the substrate, and in terms of promoting acid hydrolysis by expressing acid sites. The surface preferably has a functional group such as a phenolic hydroxyl group, a carboxyl group, a lactone (COOR) group, a sulfo group, or a phosphate group. As porous carbon materials having functional groups on the surface, woody materials such as palm, bamboo, pine, walnut, and bagasse, coke, phenol, etc., are treated at high temperatures using gases such as water vapor, carbon dioxide, and air. And activated carbon prepared by a chemical method such as a chemical method of treating at a high temperature using a chemical such as alkali or zinc chloride. As specific examples of the “carbon material”, reference can be made to specific examples of the carbon-based support described later.

When the carbon material has a phenolic hydroxyl group, a carboxyl group, or a lactone (COOR) group as a functional group on the surface, it can be identified by Boehm titration. The total of the phenolic hydroxyl group, carboxyl group, and lactone (COOR) group on the surface of the carbon material by the boehm titration can be, for example, in the range of 0.1 to 10 mmol / g. Furthermore, the amount of the carboxyl group can be in the range of 0.01 to 5 mmol / g, and the total of the phenolic hydroxyl group and the lactone (COOR) group can be in the range of 0.01 to 5 mmol / g, for example.

  Examples of the support used for the “transition metal supported catalyst” include a carbon-based support and an inorganic material support. The carbon-based support is a support in which the portion on which the transition metal is supported is made of carbon, and at least a part of the support is made of a porous material. That is, the carbon-based support used in the catalyst of the present invention is suitably at least the surface of the portion on which the transition metal is supported is made of a porous carbon material, and even if the entire support is made of a porous carbon material, Alternatively, the surface of a support made of a non-porous carbon material may be coated with a porous carbon material. The support of the carrier may be made of a material other than carbon, and may be porous or non-porous.

  Specific examples of the carbon-based solid support include activated carbon and carbon black. As the activated carbon, for example, activated carbon manufactured by Wako Pure Chemical Industries, Ltd. (for chromatograph, crushed 0.2-1 mm, crushed 2-5 mm, granular, powder, powdered acid washing, powder alkaline, powder neutral , Bar-shaped), activated carbon (granular, powder) manufactured by Kanto Chemical Co., Ltd., activated carbon (for oxidation catalyst) manufactured by Tokyo Chemical Industry Co., Ltd., activated carbon granule 4-14 mesh manufactured by Sigma Aldrich Japan Co., Ltd. ) PK, PKDA 10x30 MESH (MRK), ELORIT, AZO, DARCO, HYDRODARCO 3000/4000, DARCO LI, PETRODARCO, DARCO MRX, GAC, GAC PLUS, DARCO VAPURE, GCN, C GRAN, ROW / ROY, RO, ROX , RB / W, R, R.EXTRA, SORBONORIT, GF 40/45, CNR, ROZ, RBAA, RBHG, RZN, RGM, SX, SX Ultra, SA, D 10, VETERINAIR, PN, ZN, SA-SW, W, GL, SAM, HB PLUS, A / B / C EUR / USP, CA, CN, CG, GB, CAP / CGP SUPER, S-51, S-51 A, S-51 HF, S-51 FF, DARCO GFP, HDB / HDC / HDR / HDW, GRO SAFE, DARCO INSUL, FM-1, DARCO TRS, DARCO FGD / FGL / Hg / Hg-LH, PAC 20/200, Nippon Environment White rice cake (A, C, DO-2, DO-5, DO-11, FAC-10, M, P, PHC, element DC) manufactured by Rochemicals Co., Ltd., aldenite, carborafine, carborafine DC, honeycomb carbon White birch, Malcybon, strong white birch, refined white birch, special white birch, X-7000 / X-7100, X-7000-3 / X-7100-3, LPM006, LPM007, granular white birch (APRC, C2c, C2x, DC, G2c, G2x, GAAx, GH2x, GHxUG, GM2x, GOC, GOHx, GOX, GS1x, GS2x, GS3x, GTx, GTsx, KL, LGK-100, LGK-400, LGK-700, LH2c, MAC, MAC-W, NCC, S2x, SRCX, TAC, WH2c / W2c, WH2x, WH5c / W5c, WHA, X2M (Morcybon 5A), XRC), spherical white rabbit (X7000H / X7100H, X7000H-3 / X7100H-3, DX7-3), Kuraray Chemical ( Granular activated carbon GG / GS / GA manufactured by Co., Ltd., activated carbon GW / GL / GLC / KW / GWC for gas phase, powdered activated carbon PW / PK / PDX, Diahope manufactured by Calgon Carbon Japan (006, 006S, 007, 008, 008B, 008S, 106, 6D, 6MD, 6MW, 6W, S60, C, DX, MM, MZ, PX, S60S, S61, S70, S80, S80A, S80J, S8 0S, S81, ZGA4, ZGB4, ZGN4, ZGR3, ZGR4, ZS, ZX-4, ZX-7), diamond soap (F, G4-8, W 8-32, W 10-30, XCA-C, XCA- AS, ZGR4-C), Calgon (AG 40, AGR, APA, AP3-60, AP4-60, APC, ASC, BPL, BPL 4x10, CAL, CENTAUR 4x6, CENTAUR 8x30, CENTAUR 12x40, CENTAUR HSV, CPG 8x30, CPG 12x40, F-AG 5, Filtrasorb 300, Filtrasorb 400, GRC 20, GRC 20 12x40, GRC 22, HGR, HGR-LH, HGR-P, IVP 4x6, OL 20x50, OLC 20x50, PCB, PCB 4x10, RVG, SGL, STL 820, URC, WS 460, WS 465, WS 480, WS490, WSC 470), Ajinomoto Fine Techno Co., Ltd. BA, BA-H, CL-H, CL-K, F-17, GS-A , GS-B, HF, HG, HG-S, HN, HP, SD, Y-180C, Y-4, Y-4S, Y-10S, Y-10SF, YF-4, YN-4, YP, ZN Cataler A series, BC-9, BFG series, CT series, DSW series, FM-150, FW, FY series, GA, PG series, WA series, etc. Examples of carbon black include CRX 1444, CRX 4210, CRX 1346, REGAL 300, STERLING NS, STERLING NS-1, STERLING SO, STERLING VH, STERLING V, SPHERON 5000, SPHERON manufactured by Cabot Corporation. 6000, Black Pearls 2000, VULCAN 10H, VULCAN 1391, VULCAN 3, VULCAN 3H, VULCAN 6, VULCAN 7H, VULCAN 9, VULCAN J, VULCAN M, VULCAN XC72, VULCAN XC72R, VULCAN XC500, VULCAN XC200, VULCAN XC605, VULCAN XC305 Etc.

Moreover, a porous carbon material obtained by heat-treating mesoporous carbon typified by CMK produced using mesoporous silica as a template, coke, phenol, or coconut shell and activating with alkali or water vapor can be used. The specific surface area of these porous carbon material is preferably ^{300~2500m 2 / g, 500~2000m 2 /} g is more preferable.

  The shape and form of the solid carrier are not particularly limited, and examples thereof include powder, particles, granules, pellets, honeycombs, rings, columns, rib extrusions, and rib rings. The carrier in the form of powder, particles, granules, or pellets can be made of, for example, only the porous carbon material. On the other hand, the carrier having a honeycomb structure may be a non-porous material, for example, a surface of a support made of cordierite or the like and coated with the porous carbon material. Further, as described above, the support may be made of another porous material.

  Examples of the transition metal include ruthenium, platinum, rhodium, palladium, iridium, nickel, cobalt, iron, copper, silver, and gold. These transition metals may be used alone or in combination of two or more. From the viewpoint of high catalytic activity, those selected from platinum group metals such as ruthenium, platinum, rhodium, palladium and iridium are preferred. Furthermore, from the viewpoint of high cellulose conversion and glucose selectivity, the transition metal is particularly preferably selected from ruthenium, platinum, palladium and rhodium. From the viewpoint of high catalytic activity, ruthenium is most preferable.

  The amount of the transition metal supported on the solid support is appropriately determined in consideration of the difference in activity depending on the type of the transition metal. For example, 0.01 to 50% by mass, preferably 0.01 to 30% by mass of the catalyst. More preferably, the content is 0.01 to 10% by mass.

The solid catalyst in which the transition metal is supported on the carbon-based support used in the present invention can be prepared as follows by, for example, an impregnation method with reference to a general method for producing a metal-supported solid catalyst. The carbon-based support is vacuum dried at 150 ° C. for 1 hour. Next, water is added and dispersed, and an aqueous solution containing a predetermined amount of metal salt is added thereto and stirred for 15 hours. Thereafter, the solid obtained by distilling off water under reduced pressure is reduced to 400 ° C. for 2 hours under a hydrogen stream, and the solid obtained as a catalyst. Specific examples of metal salts include commercially available ruthenium chloride (RuCl ₃ .3H ₂ O), ruthenium nitrosyl nitrate Ru (NO) (NO ₃ ) ₃ , chloroplatinic acid (H ₂ PtCl ₆ .6H ₂ O), diammine dinitro Platinum Pt (NH ₃ ) ₂ (NO ₂ ) ₂ , palladium chloride (PdCl ₂ ), rhodium chloride (RhCl ₃ .3H ₂ O), iridium chloride (IrCl ₃ .3H ₂ O), chloroauric acid (HAuCl ₄ .4H) ₂ O), cobalt nitrate (Co (NO ₃ ) ₂ .6H ₂ O), and the like. However, it is not the intention limited to these. Since PdCl ₂ is insoluble in water, 4 equivalents of hydrochloric acid can be added to Pd and used as an H ₂ PdCl ₄ aqueous solution. Similarly, IrCl ₃ .3H ₂ O can be used by dissolving in hydrochloric acid.

Process (4)
The hydrolysis in the step (4) is performed by heating the solid catalyst having adsorbed cellulose in the presence of water, preferably at a temperature at which it is pressurized. For example, a temperature of 110 to 380 ° C. is appropriate for the heating temperature at which the pressure is applied. A relatively high temperature is preferable from the viewpoint of rapidly hydrolyzing cellulose and suppressing the conversion of the product glucose to other sugars. For example, the maximum heating (reaction) temperature is 170 to 320 ° C. More preferably, the temperature is in the range of 170 to 200 ° C, more preferably 170 to 190 ° C. The holding time at the temperature is preferably 0 to 120 minutes.

  Since hydrolysis of cellulose is usually carried out in a closed container such as an autoclave, even if the reaction is started at normal pressure, the reaction system is heated at the above temperature to be in a pressurized state. Further, the reaction can be carried out by pressurizing the inside of the sealed container before or during the reaction. The pressure to pressurize is, for example, 0.1 to 30 MPa, preferably 1 to 20 MPa, and more preferably 2 to 10 MPa. In addition to the sealed container, the reaction can also be carried out by heating and pressurizing the reaction solution with a high-pressure pump.

  The amount of water for hydrolysis is an amount capable of hydrolyzing at least the total amount of cellulose, taking into consideration the fluidity and agitation of the reaction mixture, an amount of 1 to 500 times the mass of cellulose, Preferably, the amount can be 2 to 200 times.

  The hydrolysis atmosphere is not particularly limited. Industrially, it is preferably performed in an air atmosphere, but may be performed in an atmosphere of a gas other than air, for example, oxygen, nitrogen, hydrogen, or a mixture thereof.

  The heating for the hydrolysis is terminated when the conversion rate by hydrolysis of cellulose is between 10 and 100% and the selectivity of glucose is between 20 and 90%. It is preferable in terms of enhancement. When the conversion by hydrolysis of cellulose is between 10 and 100% and the selectivity of glucose is between 20 and 90%, the heating temperature, the type and amount of solid catalyst used, the amount of water (relative to cellulose) Ratio), the type of cellulose, the stirring method, conditions, and the like, and can be determined experimentally after determining these conditions. The heating time is, for example, in the range of 5 to 60 minutes and preferably in the range of 5 to 30 minutes from the start of heating for the hydrolysis reaction under normal conditions, but is not limited to this range. . In addition, the heating for hydrolysis is such that the conversion by hydrolysis of cellulose is preferably in the range of 30 to 100%, more preferably in the range of 40 to 100%, still more preferably in the range of 50 to 100%, and most preferably. Is in the range of 55-100% and ends when the glucose selectivity is preferably in the range of 25-90%, more preferably in the range of 30-90%, most preferably in the range of 40-90%. Is appropriate.

  The form of the hydrolysis reaction may be either batch type or continuous type. The reaction is preferably carried out while stirring the reaction mixture.

  In the present invention, it is possible to produce a sugar-containing liquid containing glucose as a main component and containing a small amount of a hyperdegradation product such as 5-hydroxymethylfurfural by a hydrolysis reaction at a relatively high temperature and for a relatively short time.

  After completion of the heating, it is preferable to cool the reaction solution from the viewpoint of suppressing the conversion of glucose to other sugars and increasing the glucose yield. From the viewpoint of increasing the glucose yield, the reaction solution is preferably cooled under the condition that the selectivity of glucose is maintained in the range of 20 to 90%, more preferably in the range of 25 to 90%, and 30 to 90%. Is more preferable, and the range of 40 to 90% is most preferable.

  From the viewpoint of increasing the glucose yield, the reaction solution is preferably cooled as quickly as possible to a temperature at which the conversion of glucose into other sugars does not occur, for example, at a rate in the range of 1 to 200 ° C./min. The rate is preferably in the range of 10 to 150 ° C./min. The temperature at which the conversion of glucose into other sugars does not occur is, for example, 150 ° C. or lower, preferably 110 ° C. or lower. That is, it is appropriate to cool the reaction solution to a temperature of 150 ° C. or less, in a range of 1 to 200 ° C./min, preferably in a range of 10 to 150 ° C./min. It is more appropriate to carry out in the range of -200 ° C / min, preferably in the range of 10-150 ° C / min.

  In the production method of the present invention, the cellulose hydrolyzed solid catalyst may be a carbon catalyst, boron nitride or a transition metal-supported solid catalyst, and the saccharide-containing cellulose hydrolyzate may be a glucose-containing cellulose hydrolysate. In the present invention, the reaction mechanism of cellulose hydrolysis using, for example, activated carbon as a solid catalyst is not intended to be bound by this mechanism, but is considered as follows.

In the carbon material such as activated carbon, it is considered that the hydrophobic group (—CH) of cellulose is adsorbed on the aromatic ring present on the surface by CH—π interaction as shown below.

Further, it is presumed that acid sites such as carboxyl groups become active sites and promote hydrolysis.

Therefore, it is preferable that the solid catalyst is a carbon material such as activated carbon having an aromatic ring, and has an acid point such as a carboxyl group on the surface thereof as described above.

If glucose can be efficiently and preferentially produced from cellulose by the method of the present invention, glucose can also be converted into fuel and chemicals.

  Hereinafter, the present invention will be described in more detail based on examples. However, the examples are illustrative of the present invention, and the present invention is not intended to be limited to the examples.

Example 1
After moistening by adding distilled water (0.9 mL) to uncrystallized microcrystalline cellulose (324 mg, Avicel PH101), add 85% phosphoric acid (16.2 mL, Wako Pure Chemical Industries, Ltd.) and stirring to dissolve the cellulose. It was. Cellulose was completely dissolved in about 10 minutes. This solution was stirred at room temperature (about 22 ° C.) for several days (0-9 days) to partially hydrolyze the cellulose. Activated carbon (BA-Air, BA (Ajinomoto Fine Techno Co., Ltd., specific surface area 1230 m ² / g)) as a solid catalyst was air-oxidized in an electric furnace at 425 ° C for 10 hours (such as carboxyl groups that have weak acid points on the surface). 324 mg of oxygen-containing functional group was introduced) and stirred for 10 minutes. 30 mL of distilled water was added, and the partially hydrolyzed cellulose was adsorbed in a state where the partially hydrolyzed cellulose was in good contact with carbon (the cellulose was adsorbed on the carbon). This was filtered using a membrane filter (pore size: 0.1 μm), and phosphoric acid in the solid was removed by washing with water (300 ml). 40 mL of water was added to this sample, and the mixture was reacted in an autoclave at 180 ° C. for 20 minutes to hydrolyze the cellulose. The pH at the stage when 40 mL of water was added to the sample was 2.0 to 2.2. From this, phosphoric acid remains in the sample, and the remaining phosphoric acid may have become a catalyst for hydrolysis. After the reaction, the solution was analyzed by HPLC.

Comparative Example 1
In order to confirm the effect of the phosphoric acid treatment in Example 1, a hydrolysis reaction was performed under the same conditions as in Example 1 using cellulose not subjected to the phosphoric acid treatment.

  The results of the hydrolysis reaction of Example 1 and Comparative Example 1 are shown in FIG. The glucose yield is only 3% even when the cellulose not treated with phosphoric acid is hydrolyzed, whereas when cellulose pretreated with phosphoric acid is used, the glucose yield increases with the number of phosphoric acid treatment days. And up to 70%. This result shows the effectiveness of the phosphoric acid treatment. Results of size exclusion chromatography of the solution after 0 days, 3 days, 7 days and 9 days after the start of stirring for partial hydrolysis of cellulose (0 days after the start of stirring means 0 days of partial hydrolysis, cellulose 2 was dissolved in phosphoric acid and water was immediately added to precipitate cellulose) together with the results of size exclusion chromatography of the aqueous dispersion of microcrystalline cellulose (Avicel PH101) as a raw material. Shown in 7 and 9 days after the start of stirring, it can be seen that the molecular weight of cellulose was reduced to about 1/2 by partial hydrolysis.

Example 2
Experiments were also conducted to clarify the effectiveness of liquid cellulose adsorption on carbon catalysts. In the same manner as in Example 1, the results were obtained when cellulose was adsorbed on the carbon surface with 6 days of phosphoric acid treatment of cellulose.

Comparative Example 2
After dissolving cellulose in phosphoric acid in the same manner as in Example 1, stirring was continued at room temperature for 6 days. Distilled water (30 mL) was added thereto, cellulose was precipitated and then filtered, and phosphoric acid was removed by washing with water. Activated carbon similar to that used in Example 1 was added to this cellulose, and a hydrolysis reaction was performed under the same conditions as in Example 1. (This is a method in which liquid cellulose does not have a step of adsorbing to activated carbon.)

  The results of hydrolysis when liquid cellulose is adsorbed on the activated carbon surface (Example 2) and when not absorbed (Comparative Example 2) are shown in FIG.

  From the results shown in FIG. 3, it was revealed that adsorption of liquid cellulose (solubilized cellulose and amorphous cellulose containing partially hydrolyzed cellulose) to the carbon catalyst increases hydrolysis reactivity.

  From the above results, it can be said that it is effective to perform the hydrolysis reaction in a state where cellulose is dissolved with phosphoric acid and liquid cellulose is adsorbed on the carbon catalyst.

Example 3
The cellulose solution was hydrolyzed in the same manner as in Example 1 except that the cellulose solution was changed to room temperature and stirred at 60 ° C. for 60 minutes to perform partial hydrolysis of cellulose. The results are shown in FIG. 4 (results for 60 minutes in the figure). By carrying out the partial hydrolysis of cellulose at 60 ° C., the result of cellulose hydrolysis almost equivalent to the case of carrying out at room temperature (about 25 ° C.) in a shorter time (60 minutes) (DAY 7 (7 days) in FIG. 1) is obtained. Obtained.

Example 4
The cellulose was hydrolyzed in the same manner as in Example 3 except that the cellulose solution was stirred at 60 ° C. for 0, 30, or 90 minutes. The results are shown in FIG. By performing partial hydrolysis of cellulose at 60 ° C., a cellulose hydrolysis result almost the same as that obtained at room temperature (about 25 ° C.) (7 days) was obtained even at 30 and 90 minutes.

Example 5
Instead of BA-Air as the solid catalyst, BA ((Ajinomoto Fine Techno Co., Ltd., specific surface area 1230 m ² / g)), Norit (Cabot, specific surface area 1210 m ² / g)), Air oxi Cellulose was hydrolyzed in the same manner as in Example 3 except that it was changed to Norit (Norita was carbon which was air-oxidized in an electric furnace at 425 ° C. for 10 hours). The results are shown in FIG. In FIG. 5, as a reference example (Blank), cellulose is converted into a phosphoric acid solution, 25 mL of water is added without adding a solid catalyst to precipitate cellulose, the cellulose is washed with 300 mL of water, and 40 mL of water is added. The results of hydrolyzing cellulose by reacting at 180 ° C. for 20 minutes in an autoclave are also shown. Table 1 shows the results of Boehm titration of each activated carbon. Boehm titration was performed by a conventional method.

COOR represents a lactone, for example, assuming the structure of the lower left part of the following chemical formula.

Example 5
Cellulose was hydrolyzed in the same manner as in Example 3 except that the amount of activated carbon BA-Air as a solid catalyst was changed from 324 mg to 218 mg and 109 mg. The results are shown in FIG.

Example 6
Activated carbon (BA-Air) is added to partially hydrolyzed cellulose, and instead of adding 25 mL of distilled water after stirring for 10 minutes, ethanol, acetone or 1-propanol (25 mL each) is used to add partially hydrolyzed cellulose. Cellulose was hydrolyzed in the same manner as in Example 3 except that it was precipitated and adsorbed on activated carbon. The results are shown in FIG. In the case of using water for precipitation and adsorption of partially hydrolyzed cellulose, the yield of glucose was high.

  The present invention is useful in the field related to the production of sugars such as glucose by hydrolysis of cellulose.

Claims (15)

A step (1) of dissolving cellulose in an acid aqueous solution;
A step (2) of mixing a cellulose-hydrolyzed solid catalyst with an acid aqueous solution in which cellulose is dissolved;
Step (3) of adsorbing at least a part of cellulose on the solid catalyst, and heating the solid catalyst adsorbing cellulose in the presence of water to hydrolyze the cellulose to obtain a hydrolyzate containing saccharides Step (4),
A method for producing a saccharide-containing cellulose hydrolyzate comprising The production according to claim 1, wherein the product after at least partially hydrolyzing and dissolving at least a part of cellulose in an aqueous acid solution is subjected to step (2) during and / or after step (1). Method. The production method according to claim 2, wherein the partial hydrolysis is performed at a temperature of 40 to 80 ° C. The production method according to claim 1, wherein at least a part of the cellulose used in the step (1) has an I-type crystal structure. The method according to any one of claims 1 to 4, wherein the acid in the acid aqueous solution used in step (1) is at least one acid selected from the group consisting of phosphoric acid, sulfuric acid and hydrochloric acid. The manufacturing method according to claim 5, wherein the aqueous acid solution used in step (1) is an aqueous orthophosphoric acid solution. The manufacturing method of Claim 6 whose phosphoric acid concentration of the orthophosphoric acid aqueous solution used at a process (1) is 75% or more. The production method according to claim 1, wherein the adsorption of cellulose on the solid catalyst in the step (3) is performed by adding water or a water-soluble organic solvent to the acid aqueous solution. The manufacturing method according to any one of claims 1 to 8, wherein the solid catalyst adsorbed with cellulose obtained in the step (3) is separated from the acid aqueous solution and removed from the acid, and then subjected to the step (4). The production according to any one of claims 1 to 9, wherein the cellulose adsorbed on the solid catalyst in the step (3) includes at least one selected from the group consisting of partially hydrolyzed cellulose, amorphous cellulose and cellulose II. Method. The production method according to claim 1, wherein the cellulose hydrolyzed solid catalyst is at least one catalyst selected from the group consisting of a carbon catalyst, boron nitride, and a transition metal-supported catalyst. The production method according to claim 11, wherein the carbon catalyst is a porous carbon material, and the porous carbon material can be activated carbon or carbon black. The production method according to claim 11, wherein the transition metal-supported catalyst is a catalyst in which a transition metal is supported on a solid support, and the solid support is at least one material selected from the group consisting of a carbon-based material and boron nitride. . The manufacturing method according to any one of claims 1 to 13, wherein the mass ratio of cellulose to catalyst in the solid catalyst to which cellulose is adsorbed is in the range of 100: 1 to 10,000. The cellulose used at a process (1) is a manufacturing method in any one of Claims 1-14 which is vegetable biomass.